In recent years, a collaboration support system to enable plural users to perform cooperation work on a network is widely used in companies, government offices, municipalities and the like. The following factors of the popularization of the support system can be given.
(1) In recent years, by virtue of improvement in network environment and computer processing performance, a large amount of information can be transmitted and processed in a real time manner. Accordingly, communications such as large-amount data communication and no-delay data communication that are important in the collaboration support system, can be performed.(2) In companies, government offices and municipalities, globalization has been advanced, and situations called distributed working, in which workers related to a job are located in various places in a country or in the world, are increased. In such situations, it takes much time and labor for these workers to get together to perform a meeting. However, by introduction of the collaboration support system, the cost and time for the meeting can be avoided, and in the distributed working environment, mutual communication among the workers can be quickly realized at any time without awareness of distance in the real world.
In the collaboration support system, the users perform cooperation working via the network. The system has a “remote whiteboard” function for the users to handle a whiteboard function, a “remote presentation” function for presentation among the users in remote places, and the like.
As this collaboration support system is a network application, it is impossible to completely synchronize data among terminals in remote places due to network communication delay or the like. Further, as a conflict may occur between operations by the users in remote places, it is difficult to perform smooth cooperation working. Accordingly, to realize smooth cooperation working, some arrangement is required. Similarly, some arrangement is required upon page turning operation in the remote whiteboard function. In the page turning operation, it is necessary to satisfy the following conditions.
(A) Images on screens of all the terminals are synchronized.
(B) The timing of page turning operation is not limited (the page turning operation can be performed at any time).
(C) Page turning operation is immediately reflected in other terminals.
Arrangements to satisfy these conditions are introduced in the conventional collaboration support system. For example, a Web meeting system “Meeting Center” by WebEx Communications, Inc. (see homepage of WebEx Communications, Inc., http://www.webex.com/), a Web meeting system “Centra 7” by Centra Software, Inc. (see homepage of Centra Software, Inc., http://www.centra.com/) and the like are known. In these systems, upon page turning operation in the remote whiteboard function, a page turning operation has priority over a drawing operation, thereby the page turning operation is synchronized in all the terminals. According to the techniques described in these documents, upon page turning operation, when a drawing operation is being performed in one terminal or another terminal, the drawing operation is cancelled. By this arrangement, the page turning operation is smoothly performed in all the terminals, and the above conditions are satisfied.
However, in the above-described support systems for cooperation, the following problems occur upon page turning operation.
(1) The drawing operation in the respective terminals is forcibly cancelled.
(2) The record of the cancelled drawing operation does not remain.
As a drawing operation by a terminal is forcibly cancelled by a page turning operation of other terminal, the users of the respective terminals feel stressed since they cannot smoothly perform the drawing operation.